class_docstr: At the end of each experience, this metric reports the
  MAC computed on a single pattern.
  This plugin metric only works at eval time.
code: def __str__(self):
      return "MAC_Exp"
  
imports: from torch.nn import Module
  from typing import List, Optional
  from torch import Tensor
  from avalanche.evaluation import Metric, PluginMetric, GenericPluginMetric
label_desc: Use image node_id 2 for calling the ExperienceMAC obj's underlying member method code with example usage: obj.__str__() and returns: str